JP2001242357A - Optical semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high efficiency, a high NA and short WD lens loadable optical semiconductor device increasingly required according to a high speed of optical communication. SOLUTION: This optical semiconductor device is provided with a silicon substrate 15 having a V shaped first groove part 15b formed by etching on an upper surface part 15a, a light emitting element 11 having its optical axis in the direction of the first groove part 15b and fitted to the upper surface part 15a and an aspheric lens 23 fitted to the first groove part 15b, and the first groove part 15b is constituted of first, second slopes 15e, 15f opposite to each other, and a third slope 15g crossing at right angles with the first, second slopes 15e, 15f, and a slit 15k notched containing the first to the third slopes 15e-15g is formed on the silicon substrate 15 in the direction orthogonal to the direction of the first groove part 15b, and the aspheric lens 23 is fitted to the first and second slopes 15e, 15f in the state of projecting its part into the slit 15k, and the light emitting element 11 is made optical communication possible through the aspheric lens 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device used in the field of optical communication, and more particularly, to an optical semiconductor device provided with a high NA (numerical aperture) lens for high-speed, large-capacity optical communication. About.

[0002]

2. Description of the Related Art As shown in FIG. 7, in a conventional optical semiconductor device 50, light 52 radiating from an end face of a light emitting element 11 and radiating from the end face thereof is applied to one end face of an optical fiber 14 using a ball lens 53. A light coupling structure for condensing light was configured.

In this optical semiconductor device 50, a silicon (Si) substrate 55 shown in FIGS. 8A to 8C has been used. The silicon substrate 55 has a V-shaped groove 55b having a substantially V-shaped (trapezoidal) cross section on the upper surface 55a. The V groove 55b is formed by anisotropically etching the surface of the silicon substrate 55 using a resist mask formed by photolithography. The silicon substrate 55 has a characteristic inclination angle (θ) in which the edge of the V-groove 55b with the upper surface 55a comes from the silicon crystal structure.
Slope 55 with a slope of 54.7 degrees for both 1, 2, and 3)
e, 55f, and 55g.

[0004] The optical semiconductor device 50 includes a light emitting element 11 formed on a silicon substrate 55 shown in FIG.
The light emitting device 11 and the ball lens 53 are positioned and positioned in the nearby upper surface 55a, and the ball lens 53 is positioned in the V groove 55b.

[0005]

However, in recent years, optical communication has been required to increase the communication speed, and the optical semiconductor device 50 constituting the optical coupling structure between the light emitting element 11 and the optical fiber 14 has been required. The optical coupling loss has a great effect, hindering high-speed optical communication. For this purpose, the applicant has proposed to use an aspheric lens capable of low-loss optical coupling instead of the ball lens 53.

As shown in FIGS. 9A and 9B, the optical semiconductor device 60 has a configuration in which an aspheric lens 63 is mounted and fixed in a V groove 55 b of a silicon substrate 55 instead of the conventional ball lens 53. As shown in FIG. 10, the aspherical lens 63 is made of a finite system lens made of optical glass, and includes a lens body 63a having a biconvex aspherical surface and an edge 63b around the lens body 63a. ,
Its outer diameter (φ) is 1.0 mm, lens thickness (tc) is 0.81, and optical length (L = L1 + tc + L2) is 3.56.
mm, the focal length (L2) is about 2 mm, the NA (numerical aperture) is 0.45, and the magnification (m) is 3. The distance (L1) from the object point to the vertex of the lens surface has a characteristic value of 0.3. Here, NA is generally represented by the following equation. NA = n sin θ where θ is the angle between the light beam having the largest divergence and the optical axis among the light beams emitted from the object point on the axis, and n is the refractive index of the medium having the object point. And the larger the NA,
The resolution is increased, and the efficiency of optical coupling can be increased. Further, by making the lens an aspherical shape, the influence of aberration can be suppressed with one lens.

The optical semiconductor device 60 having the aspherical lens 63 having the NA of 0.45 as shown in FIG.
The outgoing light 52 spread out from the end face of the light emitting element 11 passes through the aspheric lens 63 and focuses on the end face of the optical fiber 14 (see FIG. 7), thereby improving the loss in optical coupling as compared with the ball lens 53. Light can be transmitted.

By the way, in such an optical semiconductor device 60, in order to cope with high-speed and large-capacity optical communication and maximize the characteristics of the aspherical lens, the NA of the aspherical lens is further increased. It was necessary to shorten WD (working distance = L1), which is the distance from the light emitting element 11 to the aspherical lens.

The proposed optical semiconductor device 70 shown in FIG.
Here, the aspherical lens 23 having a high NA (numerical aperture) and a short WD is mounted on a silicon substrate 55. As shown in FIG. 11, the aspheric lens 23 is an infinite lens made of optical glass, and has a biconvex aspheric surface.
a, and an edge portion 23b around the periphery of the lens body 23a. The outer diameter (φ) is 1.0 mm, the lens thickness (tc) is 0.81 mm, the focal length (L2) is infinite (∞), The NA (numerical aperture) has a characteristic value of 0.60. In the case of an aspherical lens, the precision of optical axis alignment is generally required to be stricter as the NA becomes higher. However, in this aspherical lens 23, since light emitted from one side becomes parallel light, optical axis alignment is relatively easy. You can do it.

[0010] However, as shown in FIG.
If the aspherical lens 23 of A is mounted and fixed as it is in the V groove 55b of the conventional silicon substrate 55, there is a problem that a portion (H) that interferes with the inclined surface 55g of the V groove 55b occurs. For this reason, there is a problem that the aspherical lens 23 having a high NA and a short WD and a high NA making full use of the characteristics of the aspherical lens cannot be mounted on the silicon substrate 55.

As shown in FIG. 13, focusing on the outer diameter of the aspherical lens 23, it is conceivable to reduce the outer diameter (φ) so that the interference portion H does not occur. However, with the intention of maintaining a high NA,
It is necessary to further shorten the WD. As a result, the aspherical lens 23 is simply reduced to a similar shape.
There is a problem that the generation of the interference portion (H) with 5c cannot be avoided.

An object of the present invention is to provide an optical semiconductor device capable of mounting a lens with a high NA and a short WD aiming at higher efficiency, which is required more and more in accordance with the increase in speed and capacity of optical communication. It is in.

[0013]

At least one of the above objects is attained.
As a first solution to solve the above problem, a silicon substrate having a V-shaped first groove formed on one surface by etching, an optical axis in the direction of the first groove, and mounting on this one surface Provided, and a lens attached to the first groove, wherein the first groove has opposed first and second optical elements.
And a third inclined surface orthogonal to the first and second inclined surfaces. The silicon substrate has first to third inclined surfaces in a direction orthogonal to the direction of the first groove. A notched second groove including a surface is formed, and the lens is attached to the first and second inclined surfaces with a part of the lens protruding into the second groove, and the optical element is inserted through the lens. Optical communication.

As a second solution, the second groove is formed in a concave shape across the silicon substrate.

As a third solution, the edge of the lens is attached to the side wall of the second groove so as to abut.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical semiconductor device 10 according to one embodiment of the present invention will be described below with reference to FIGS.
Note that the same reference numerals are given to portions having the same configuration and the same functions as those of the above-described optical semiconductor device, and description thereof is omitted. As shown in FIG. 1, the optical semiconductor device 10 has an upper surface portion (one surface) 15.
a-shaped first groove 1 formed in a.
5b is provided. The silicon substrate 15 is made of silicon (Si) single crystal, and its upper surface 15a has a (111) crystal plane, and the surface of the first groove 15b has a (100) crystal plane. As shown in FIGS. 1, 5A to 5C, the first groove 15b
Is a rectangular small bottom surface 15d, a first inclined surface 15e and a second inclined surface 15f opposed to each other, surrounding the small bottom surface 15d, and a first orthogonally intersecting first and second inclined surface 15e, 15f. 3 of inclined surfaces 15g. The first to third inclined surfaces 15e, 15f, and 15g, which are the (100) crystal planes of the first groove 15b, are formed on the (111) crystal surface of the upper surface 15a by using a resist mask formed by photolithography. It is formed by anisotropically etching the surface. Therefore, the inclination angle between the small bottom surface 15d and each of the inclined surfaces 15e, 15f, and 15g has a unique inclination angle (54.7 degrees for each of θ1, θ2, and θ3) derived from the structure of the silicon crystal.

Further, the first, second and third grooves are formed on the silicon substrate 15 in a direction orthogonal to the direction of the first groove 15b.
A concave slit (second groove) 15k cut out including the inclined surfaces 15e, 15f, and 15g is formed to cross. The slit 15k is provided with a side wall 15j perpendicular to the top surface 15a and the small bottom surface 15d. In addition, the upper surface 15a
Is a large first region 1 adjacent to the third inclined surface 15g.
5m and small second and third regions 15n and 15p adjacent to the first and second inclined surfaces 15e and 15f, respectively.

As shown in FIG. 1, a light emitting element 11 such as a semiconductor laser, which is one of the optical elements, is mounted on a first region 15m of an upper surface 15a of a silicon substrate 15. The light emitting element 11 has a third region on the first region 15m.
Of the light 12 emitted from the end surface of the first groove portion 15b.
And the second inclined surfaces 15e and 15f.

Next, as shown in FIGS. 1, 4A and 4B, a high NA (numerical aperture) aspherical lens 23 (see FIG. 11) is provided in the first groove 15b. . The aspherical lens 23 is positioned and fixed by the first and second inclined surfaces 15e and 15f so that the optical axis thereof coincides with the optical axis of the light emitting element 11. Further, a part of the aspheric lens 23 is protruded into the slit 15k so that the light 12 emitted from the light emitting element 11 becomes parallel light 12 'when passing through the aspheric lens 23. Therefore, the aspherical lens 23 is placed in the first groove 15b and the slit 15k in the vicinity of the light emitting element 11 side, that is, in a state where the working distance (WD) is shortened, without generating the interference portion (H). It is mounted and fixed. The parallel light 12 ′ emitted from the aspheric lens 23 is incident on one end surface of the optical fiber 14.

Next, a method of assembling the optical semiconductor device 10 thus configured will be described. First, FIGS. 5A to 5C
Is prepared. The silicon substrate 15 has a substantially V-shaped (trapezoidal) first groove 1 formed on a substrate made of silicon single crystal by anisotropic etching.
5b is formed. First to third inclined surfaces 15e, 15
f, the inclination angles (θ1, θ2, θ3) of 15g are all 5
4.7 °. The slit 15k of the silicon substrate 15 is precisely ground by a dicing saw or the like.

Next, the light emitting element 11 and the high NA aspherical lens 23 are mounted on the silicon substrate 15. Light emitting element 11
The optical axis is adjusted with high precision by a jig (not shown) in the first region 15m of the upper surface portion 15a, and is attached and fixed. The aspherical lens 23 has its edge 23b positioned in the direction orthogonal to the optical axis by the first and second inclined surfaces 15e and 15f. That is, positioning adjustment is performed in the horizontal direction (X-axis direction) and the vertical direction (Y-axis direction) with respect to the optical axis. Further, the aspherical lens 23 is moved along the optical axis direction from the first and second inclined surfaces 15e and 15f to the slit 15k and the third inclined surface 15g while being optically adjusted and positioned (Z-axis). Direction), and fixed at predetermined positions of the first groove 15b and the slit 15k of the silicon substrate 15.

The operation of the optical semiconductor device 10 constructed and assembled as described above will be described. The light 12 radially emitted from the end face of the light emitting element 11 is a high NA aspheric lens 23.
Incident on one surface without any interruption, and exits from the other surface of the aspheric lens 23 as parallel light 12 ′. Then, the parallel light 12 ′ is incident on one end face of the optical fiber 14.

Incidentally, in the optical semiconductor device 10, the slit 15k is formed in a concave shape completely across the silicon substrate 15, but if there is no interference portion (H) in the mounting portion of the aspherical lens 23, It is not necessary to completely traverse the silicon substrate 15, and for example, the slit may be formed in the shape shown in FIG. That is, as shown in FIG.
The rotating member having the dimension of the radius R1 may be cut so that the rotation axis thereof is fixed and the silicon substrate 15 is dug into a circular shape. The slit 15k 'of the formed silicon substrate 15 has a concave cross section in a direction orthogonal to the optical axis direction,
The cross section becomes curved in the optical axis direction. Therefore, slit 1
5k 'is the first, second, and third regions 15 of the upper surface 15a.
m, 15n, and a part of 15p are respectively connected.

Although the optical semiconductor device 10 has a high NA aspherical lens 23 mounted thereon, it is not necessarily limited to this, and is applied to a conventional optical aspherical lens which needs to avoid an interference part. Is also good. For example, an aspherical lens has an outer diameter (φ) of 1.0 mm and a lens thickness (t).
c) is 0.81, the optical length (L) is 3.98 mm, the focal length (f) is about 2.91 mm, the NA (numerical aperture) is 0.5,
A finite system having a characteristic value with a magnification (m) of 5 and a distance (L1) from the object point to the vertex of the lens surface of 0.25 may be used.

In the optical semiconductor device 10, the light emitting element 1
Although the optical semiconductor device on the transmitting side equipped with 1 has been described, it may be an optical semiconductor device on the light receiving side incorporating a light receiving element (optical element) such as a photodiode.

In the optical semiconductor device 10, the side wall 15j formed by cutting a part of the third inclined surface 15g of the silicon substrate 15 is formed on the edge portion 23 of the high NA aspherical lens 23.
b may be brought into contact and positioned.

The optical semiconductor device 10 configured as described above
Has the following effects. 1) First groove 15b
Is formed on the silicon substrate 15 having the first, second and third inclined surfaces 15 in a direction orthogonal to the direction of the first groove 15b.
e, 15f, slit 15k cut out including 15g
Are formed, and the first and second inclined surfaces 15e, 15e are formed in a state in which the aspherical lens 23 partially projects into the slit 15k.
By mounting the lens at 15f, the aspherical lens 23 with a high NA can be mounted at a desired position near the light emitting element 11, so that the effect of the aspherical lens 23 is maximized and the non-aspherical lens with a short WD is used. The spherical lens 23 can be mounted on the silicon substrate 55. Therefore, the optical semiconductor device 10 can achieve high optical coupling efficiency corresponding to high speed and large capacity in optical communication.

2) The slit 15k can be easily formed into a concave shape by simply moving the cutting teeth in one direction (vertical direction) across the silicon substrate 15 by cutting with a dicing saw or the like.

3) Since the edge 23b of the aspherical lens 23 is attached to the side wall 15j of the slit 15k in contact with the side wall 15j, the side wall 15j can be used in addition to the first and second inclined surfaces 15e and 15. Since positioning in the optical axis direction (Z axis) can be performed, positioning and fixing can be performed more accurately.

[0030]

As described above, the optical semiconductor device of the present invention has a silicon substrate having a V-shaped first groove formed on one surface by etching, and an optical axis in the direction of the first groove. With an optical element mounted on this one side,
A lens attached to the first groove, the first groove comprising first and second inclined surfaces facing each other, and a third inclined surface orthogonal to the first and second inclined surfaces. The silicon substrate is formed with a second groove portion cut out including first, second and third inclined surfaces in a direction orthogonal to the direction of the first groove portion, and the lens is provided with a second groove portion. Attaching the lens to a desired position near the optical element by attaching the optical element to the first and second inclined surfaces while partially projecting into the optical element so that the optical element can perform optical communication via the lens. Therefore, the lens can be mounted on a silicon substrate so as to make use of the characteristics of a lens having a high NA and a short WD.
Therefore, with this optical semiconductor device, it is possible to increase the efficiency of optical coupling corresponding to an increase in speed and capacity in optical communication.

Further, since the second groove is formed in a concave shape across the silicon substrate, it is simply cut out in one direction, so that it can be processed simply and accurately.

Also, since the edge portion of the lens is mounted on the side wall of the second groove so as to abut, the positioning in the optical axis direction (Z axis) can be performed by the side wall. Optical adjustment can be performed easily and more accurately.

[Brief description of the drawings]

FIG. 1 is an overall view of an optical semiconductor device according to an embodiment of the present invention.

FIG. 2 is a left side view of the optical semiconductor device according to one embodiment of the present invention.

FIG. 3 is a front view of the optical semiconductor device according to the embodiment of the present invention as viewed from the optical fiber side.

FIG. 4A is a longitudinal sectional view of the optical semiconductor device according to the embodiment of the present invention, taken along the optical axis direction;
Is a longitudinal sectional view in a direction orthogonal to the optical axis.

5A is a plan view of the optical semiconductor device according to the embodiment of the present invention before a lens is mounted, and FIG.
Is a left side view thereof, and FIG. 5C is a front view thereof.

FIG. 6 is a front view showing a modified example of the concave groove of the optical semiconductor device according to the embodiment of the present invention.

FIG. 7 is a schematic sectional view showing a conventional optical semiconductor device.

8 shows a silicon substrate used in a conventional optical semiconductor device, FIG. 8A is a plan view thereof, FIG. 8B is a left side view thereof, and FIG. 8C is a front view thereof.

FIG. 9A shows the proposed optical semiconductor device.
FIG. 7B is a longitudinal sectional view along the optical axis direction, and FIG. 7B is a longitudinal sectional view in a direction orthogonal to the optical axis.

FIG. 10 is an explanatory diagram illustrating an optical system of a lens used in the proposed optical semiconductor device.

FIG. 11 is an explanatory diagram illustrating an optical system of a lens having a high NA.

FIG. 11A is a longitudinal sectional view along the optical axis direction of the proposed optical semiconductor device including the high NA lens, and FIG. 11B is a longitudinal sectional view in a direction orthogonal to the optical axis. .

FIG. 13 is a longitudinal sectional view along an optical axis direction for explaining an optical semiconductor device provided with a conventional lens or a high NA lens.

[Explanation of symbols]

 Reference Signs List 10 optical semiconductor device 11 light emitting element (optical element) 15 silicon substrate 15a upper surface (one surface) 15b first groove 15e first inclined surface 15f second inclined surface 15g third inclined surface 15k slit (second groove) ) 15j Side wall 23 Aspherical lens 23b Edge part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H037 AA01 BA03 CA15 DA05 DA12 5F041 AA06 EE04 EE15 FF14 5F073 AB27 AB28 BA02 DA22 DA35 EA29 FA08 FA13 FA16 FA23 5F088 BA03 BB01 GA04 JA03 JA12 JA14

Claims (3)

[Claims] 1. A silicon substrate having a V-shaped first groove formed on one surface by etching, an optical element having an optical axis in a direction of the first groove and mounted on the one surface, A lens attached to the first groove, wherein the first groove comprises a first and a second inclined surface facing each other, and a third inclined surface orthogonal to the first and second inclined surfaces. The silicon substrate is formed with a second groove portion cut out including the first, second, and third inclined surfaces in a direction orthogonal to the direction of the first groove portion. Is mounted on the first and second inclined surfaces with a part thereof protruding into the second groove, and the optical element is capable of optical communication via the lens. Semiconductor device. 2. The optical semiconductor device according to claim 1, wherein said second groove is formed in a concave shape across said silicon substrate. 3. The optical semiconductor device according to claim 1, wherein an edge portion of the lens is attached to a side wall of the second groove so as to abut.